Prepping for Daophot and Allstar

The calm before the storm?
December 03, 2007

Before beginning daophot, we must prepare a series of files.

1. The Image Files

Luckily, we have updated daophot and it now acccepts fits images!
Please note that during the course of the photometry, we will make a
series of potentially large ascii files as well as making at least 2 copies of the
original fits image. Please make sure you have enough free disk space to do this.
The errors output by the program when the disk is full are quite difficult
to interpret correctly.

2. The OPTions Files

Daophot and Allstar each require a file that contains a series of image specific parameters.
These files can be automatically generated with an IDL program written by David Nidever.

However, the headers for the Fan Mountain data contain none of the required information.
So, we're going to do this the old fashioned way.

Tony Sohn wrote a Fortran script,
mkopt.f , that will create the opt files for
daophot and allstar. This code requires a very specific preparation file that we nominally
call night#.log. In this file you will collect a series of image parameters that will be complied
into the opt files by mkopt.f .

The read noise and gain of the detector should be available in the Fan Moutain User's Manual.

The fwhm can be computed as the average of a series of stars using the 'r' task in iraf's imexam.

The High Limit is the saturation limit of the chip. The best way to estimate this is by examining the radial profile
of a saturated star and determining the point at which it becomes saturated.

The Filter should be available in the log.

A CAVEAT: It is very tempting to take the saturation limit to be the actual limiting count of the amplifier.
In practice, however, this is not the actual saturation limit of the stars.

Once this file is put together you can compile and run mkopt.f:

> mkopt
Log file ?
Pal11.log

Now you will have a obj????.opt and obj????.als.opt files for each image in your file.
Daophot and Allstar look for these files as daophot.opt and allstar.opt respectively.
Thus you will need to change the name of the file for each run in daophot.

The obj????.opt file is for Daophot. You should recognize some of your inputs in the .log file for mkopt:

The photo.opt file is a list of apertures for aperture photometry to be performed in daophot.
Daophot will read in this file automatically if it has the name photo.opt.
The default file is adequate for our purposes here: